This invention relates to production of high octane fuel from naphtha by hydrocarbon cracking and etherification. In particular, it relates to methods and reactor systems for cracking C.sub.7 + paraffinic and naphthenic feedstocks, such as naphthenic petroleum fractions, under selective reaction conditions to produce etherifiable isoalkenes.
There has been considerable development of processes for synthesizing alkyl tertiary-alkyl ethers as octane boosters in place of conventional lead additives in gasoline. The etherification processes for the production of methyl tertiary alkyl ethers, in particular methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) have been the focus of considerable research. It is known that isobutylene (i-butene) and other isoalkenes (branched olefins) produced by hydrocarbon cracking may be reacted with methanol, ethanol, isopropanol and other lower aliphatic primary and secondary alcohols over an acidic catalyst to provide tertiary ethers. Methanol is considered the most important C.sub.1 -C.sub.4 oxygenate feedstock because of its widespread availability and low cost. Therefore, primary emphasis herein is placed on MTBE and TAME and cracking processes for making isobutylene and isoamylene reactants for etherification.